High‐Rate 3D Printing of Shear‐Thickening Fluids and Dense Suspensions Via Dynamic Jamming Suppression

ABSTRACT Shear‐thickening fluids (STFs) are responsive materials that reversibly increase in viscosity at high shear rates. This passive response makes STFs particularly attractive for impact protection and vibration damping, and their direct integration into 3D‐printed structures offers a route to complex, highly customizable architectures with preprogrammed load‐dependent responses. However, this same mechanism has historically created significant processing challenges. During extrusion, high shear rates within the nozzle induce shear thickening, leading to defects, limited flow rates, and clogging. To overcome this paradox between STF processing and application, we demonstrate that in situ vibrations can temporarily suppress shear thickening during extrusion without compromising functional performance. The vibration‐assisted nozzle enables the fabrication of STF‐embedded structures with extrusion speeds up to higher than conventional methods. Using this method, we fabricate rate‐adaptive composite structures and extend the method to improve the printability of other challenging, filler‐laden materials that display jamming behaviors, including carbon fiber composites, ceramic pastes, and cement‐based inks. This vibration‐assisted strategy provides a non‐damaging route for 3D printing highly loaded inks. STF‐embedded structures produced using this approach hold particular promise for next‐generation protective systems in aerospace, defense, healthcare, and athletics that require load‐responsive impact absorption and vibration mitigation.